Hi everyone,
i had this issue and i've achived to find a partial solution, the problem of this solution is that i should do it each time that i boot the system and before it started automatically when i booted the virtual machine.
All this started one day that i was to boot my virtual machine like i always did and appeared this error (Image 1)
Image 1
I read this vlog: https://salmorejogeek.com/2016/03/30/como-mostrar-el-menu-del-grub-cuando-ubuntu-es-el-unico-sistema...
and in the last pharagraph of this vlog said: " Usually the last distros Linux are saved the two or three last kernels for always having some diferent at the last with which it boot in case to failure, as it is updated it is deleted the oldest..." And for this, i though to reboot the system with one of the oldest kernels verisions.
So in the GRUB menu, i selected the "Advanced Options for Ubuntu" (image 2)
Image 2
And i chose one of the oldest version: "Ubuntu, with Linux 4. 15. 0-58-generic" (image 3) and my system started to work properly.
Image 3
i hope yours replies and that this help you, regards bros.